CA2189663A1 - Open-cell foams in roofing systems - Google Patents

Open-cell foams in roofing systems

Info

Publication number
CA2189663A1
CA2189663A1 CA002189663A CA2189663A CA2189663A1 CA 2189663 A1 CA2189663 A1 CA 2189663A1 CA 002189663 A CA002189663 A CA 002189663A CA 2189663 A CA2189663 A CA 2189663A CA 2189663 A1 CA2189663 A1 CA 2189663A1
Authority
CA
Canada
Prior art keywords
foam
membrane
percent
roofing system
alkenyl aromatic
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
CA002189663A
Other languages
French (fr)
Inventor
Daniel D. Imeokparia
Creston D. Shmidt
Kyung W. Suh
Michael J. Ennis
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Dow Global Technologies LLC
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of CA2189663A1 publication Critical patent/CA2189663A1/en
Abandoned legal-status Critical Current

Links

Classifications

    • EFIXED CONSTRUCTIONS
    • E04BUILDING
    • E04DROOF COVERINGS; SKY-LIGHTS; GUTTERS; ROOF-WORKING TOOLS
    • E04D11/00Roof covering, as far as not restricted to features covered by only one of groups E04D1/00 - E04D9/00; Roof covering in ways not provided for by groups E04D1/00 - E04D9/00, e.g. built-up roofs, elevated load-supporting roof coverings
    • E04D11/02Build-up roofs, i.e. consisting of two or more layers bonded together in situ, at least one of the layers being of watertight composition

Abstract

Disclosed is a roofing system (20) for structure such as a building. The system (20) comprises a roof deck (10), a plurality of panels (12) of an extruded alkenyl aromatic polymer foam above and adjacent the deck (10); and a substantially waterproof membrane (14), above and adjacent to the foam. The foam has an open cell content of 30 percent or more. The foam provides excellent mechanical support for the membrane (14), and is water resistant. The foam further has a high heat distortion temperature, and is substantially free of distortion at high service temperatures encountered in roofing systems. Further disclosed is a recovery roofing system employing the above foam. Further disclosed are processes for constructing a new roofing system and a recovery roofing system.

Description

WO 96100335 ,~ ~ 8 ~ 66 3 1 "" . o ,~,., OPEN-r ELL FOAMS IN ROOFING SYSTEMS
This inventlon relates to a method of employing an extruded, open-~ell alkenyl aromatic polymer foam in roofi ng systems.
Roofing systems typically comprise multiple layers of various materials conflgured to protect and optionally to insulate a roof deck or upper surface of a structure or building The roofing system protects the deck and the interior of the structure from the weather, including wind, rain, and other precipitation.
The critical component of a roofing system is the membrane. The membrane is a sheet or mat of a solid, elastomeric substance which protects the deck from the aforementioned weather elements. Conventional membranes include those of EPDM
~ethylene-propylene-diene elastomer), modified bitumen, and plasticized polyvinylchloride.
The membrane may be dark, medium, or light in color, but is usually dark.
When installing a new roofing system, the membrane is placed or laid on top of the roof deck. A protective layer may be typically inserted between the membrane and the deck. The protective layer may take the form of an insulative plastic foam or, more commonly, a non-foam material such as a wood or wood composite panel. Commercially-employed plastic foams include polystyrene bead foam, closed-cell extruded polystyrene foam, and closed-cell polyisocyanurate and polyurethane foams.
Optionally, a paving layer may be placed or laid on top of the membrane. rhe paving layer typically comprises materials such as gravel or stone ballast, shingles, brick, or concrete. Thepavinglayerfunctionstophysicallyprotectthemembranefromfoottrafficand direct exposure to sunlight and the weather.
When replacement or recovery roofing systems are installed In existing structures or buildings, they are often installed over existing roofing systems. In a typical recovery system, a protective layer is applied or laid on top of the existing roofing system, usually an old membrane or an old paving layer; a new membrane is applied or laid on top of the protective layer; and, optionally, a new paving layer is applied on top of the new membrane. The protective layer protects the new membrane from the rough and uneven surfaces often encountered on the upper surfaces of existing roofing systems, provides mechanical support underneath the new membrane, and, in the case of plastic foams, provides additional insulation.
A problem commonly encountered with roofing systems is rupture of the membrane due to distortion or deterioration of the protective layer underneath the membrane. Thedistortionandd~.~,io,~ir,nproblemsarisefromtheexposureofthe protective layer to extreme heat from direct sunlight or moisture buildup due to weather exposure~ The membrane, which is typically dark and elastomeric, absorbs significant heat SUBSTITUI E SHEET ~E 26~
.. .. . ..

WO 9610033~ ~ 2 1 8 9 6 6 3 PCT~S9~/n~261 " .. ..
from the sunlight, and further does notallow IQr timely escape ot molsture trapped underneath it. When the insulating andlor protective layer be~omes dlstorted or deteriora~ed, the membrane and the protective layer may separate to form VOld pockets, which leave the membrane with diminished mechanical support on its undersurface. The diminished support renders the membrane more subject to rupture.
The source of distortion and deterroration prob~ems of the materlal in the Lprotective layer varies according to the nature of the material. Some materials are susceptible to heat, some are susceptible to moisture, and some have inherently low mechanical strengt~1.
Extruded~ closed-cell polystyrene foams offer excellent mechanical strength and water resistance, but can become distorted at high service temperatures ~greater than 1 ~5F) due to their relatively low heat distortion temperature. Such high service temperatures are typically encountered under a dark membrane in direct sunlight.
~xpanded polystyrene bead foamstypically better maintain their shape in a high temperature environment than extruded, closed-cell polystyrene foams because they typically have better bowing characteristics. Their bowing characteristics are better because the coalesced expanded bead structure allows for greater mechanical relaxation compared to the solid, cellular form of extruded, closed-cell foams. However, the coalesced expanded bead structure also results in lower mechanical strength and lower resistance to water transmission Closed-cell polyisocyanate foams have high heat distortion temperatures (250F-27~F)(12tC-135C),buthavepoormoistureresistance. Moistureweakensthecellular structure of such foams, and renders them subject to physical deterioration over time.
Moisture also diminishes the insulation value of the foam. They are also relatively friable, which affects their handling characteristics.
Closed-cell polyurethane foams, like closed-cell polyisocyanate foams, have highheat distortion temperatures and poor moisture resistance. They are also relatively friable, which affects their handling characteristics.
Wood panels and wood composite panels have high heat distontion temperatures, but have poor moisture resistance. Moisture weakens the wood, and renders it subject to physical deterioration over time. Further, the panels provide little insulation compared to foams.
It would be desirable to have a foam which could be deployed underneath a membrane in a roofing system It would further be desirable if such foam had a heat distortion temperature of 190^F 188oc)or more. It would further be deslrable if such ioam had excellent moisture resistance and mechanical strength similar to that of extruded, closed-cell polystyrene foams.
According to the present invention there is a roofing system for a structure Theprocess compnses a roof deck; a protective layer of a plurality of panels of an extruded alkenyl aromatic polymer foam situated above and adjacent the deck; and a substantially waterproof SL18STITUTE SHEET ~IWLE 26~

~ W096/00335 2189~3` P~ 0"~;1 membrane situated above and adlacent to the foam. The foam comprises an alkenyl aromatlc polymer materia~ having greater than 50 percent by weight alkenyl aromatic monomeric unlts, and has from 30 to 80 percent open cell content, Further according to the present invention there is a recovery roofing system for a structure. The roofing system comprises a pre-existing roofing system; a protective layer of a plurality of panels of an extruded alkenyl aromatic polymer foam situated above and adjacent the pre-existi ng roofing system; a substantially waterproof second membrane situated above and adjacent to the foam The pre~existing roofing system comprises a roof deck and a first membrane situated above and ad jacent the roof deck Further according to the present invention there is a process for constructing aroofing system for a structure rhe process comprises providing a roof deck; applying above and adjacent to the upper surfa~e of the roof deck a protective layer of a plurality of panels of an extruded alkenyl aromatic polymer foam; and applying a substantially waterproof membrane above and adjacent to the upper surface of the foam Further according to the present invention there is a process for constructing arecovery roofing system for a structure The process comprises providing a pre-existing roofing system; applying above and adjacent to the upper surfa~e of the pre-existing roofing system a protective layer of a plurality of panels of an extruded alkenyl aromatic polymer foam; and applying above ~on top of) and adjacent to the upper surface of the foam a second membrane which is substantially waterproof. rhe pre-existing roofing system comprises a roof deck and a first membrane situated above and adjacent the roof deck.
In the above systems and processes, the protective layer is situated adjacent toand preferably contiguous to the membrane Being contiguous is preferred because maximum physical protection is afforded the membrane.
When any component (roofing decks, membranes, protective layers, paving layers) of a roofing system or replacement roofing system is described as being adjacent to another component, they are situated in parallel and proximity to one another, but may or may not be in direct physical contact. When a component is described as being contiguous to another component, they are in direct physical contact.
The features of the present invention will be better understood upon reviewing the drawings together with the remainder of the specification.
Figure 1 is a cross-sectional view of a roofing system of the present invention Figure 2 is a cross-sectional view of a recovery roofing system of the present invention.
Figure 3 is a cut away view of the roofing system illustrated in Figure 1.
Figure 4 is a cut away view of the recovery roofing system illustrated in Figure 2 The present invention affords new roofing systems and recovery roofing systems with enhanced longevity and performance. Longevity and performance are enhanced by SUBSTITUT~' SHEET (RU~E 26~
... .. ... . .. ...... ......

218~663 WO 96/00335 ~ .,'0~261 improving the physical support and Integrity of the rooflng membrane. The Improved physlcdl support and integrity make the formation of membrane rupture less likely, resulting in a reduced incidence of water leakage through the roofing system.
The physical support and integrity of the membrane is enhanced by employlng d protective layer of an extruded, open-cell alkenyl aromatic polymer foam underneath the membrane The foam offers excellent heat and moisture resistance and mechanlcal strength The foam further enhances the heat insulation of the roofing system Figures l and 3 illustrate a new roofing system 2û of the present invention Roofingsystem20comprisesinsequencearoofdecklO,aprotective(foam)layer12,a membranel4,andapavinglayerl6stackedoneontopoftheother. Protectivelayer12 comprises the extruded, open-cell alkenyl aromatic foam described herein. If insulation additionaltothatprovidedbyprotectivelayerl2isdesired,aninsulatingfoamplasticmaterial such as an extruded, closed-cell alkenyl aromatic polymer foam may be provided between protectivelayerl2androofingdeck10. Itisunderstoodthatpavinglayersintheembodiments herein are optional Flgures 2 and 4 illustrate an embodiment of a recovery roofing system 34 of the present invention. In employing a recovery roofing system, the cost o~ removing the pre-existing system is avoided by placing a new roofing system directly on top of the pre-existlng roofing system. The pre-existing roofing system comprises a roof deck 22, a first membrane i4.
and a firstpaving layer 26. The new roofing system comprises protective layer 28, second membrane 30, and second paving layer 32. If insulation additional to that provided by protective~ayer28isdesired,anotherlayerofaninsulatingfoampiasticmaterialsuchasanextruded, closed-cell alkenyl aromatic polymer foam may be provided between the first paving layer 26 and protective layer 28.
The extruded, alkenyl aromatic polymer foam provides enhanced performance In roofingsystemsoverothermaterialsemployedinprotectivelayersforroofingmembranesin the prior art.
The extruded, open-cell foam offers moisture resistance and mechanical strength similartothatofa..",~:",~."d")gextruded,closed-cellalkenylaromaticpolymerfoam,butalso affords a higher heat distortion temperature. The open-cell foam has a heat distortion temperatureupto210F~99C),whiletheclosed-cellfoamhasoneofuptol75~F(79C).
Though not bound by any particular theory, the higher heat distortion temperature is belleved due to the open-cell structure, which allows cell gas pressure to be relieved more readily than a closed-cell structure.
The extruded, open-cell foam affords a better heat distortion temperature than a",ondi"g expanded bead polystyrene foam, and has better mechanical strength and exhibits much lower water ~ ic~n The extruded, open-cell foam has a unitary, cellular structure rather than a coalesced bead structure like the bead foam.

SUBSTITUTE SHEET (RULE 26) ~ W09610033~ ~189663 r.~u~ s.o.~rl The extruded, open-cell foam exhibits much better moisture resistance than a closed-~ell polyisocyanate foam or polyurethane foam, and, thus, is much less sub~ect to physical deterioration The open-cell foam affords a lower range of heat distonion temperatures than the polyiso~yanate or polyurethane foam, but the afforded range is entirely sufficient for temperatures ~ommonly encountered in roofing applications Funher, with respect to the polyurethane foam, the open-cell foam is more rigid, which makes it more effective in providing mechanical suppOn Funhe~, the open-cell foam has friability characteristics~lessfriability)superiortothoseotpolyisocyanurateandpolyurethanefoams The extruded, open-cell foam exhiblts much bettef moisture resistance than a 1û
wood or wood composite panel. The open-cell foam affords heat distortion temperatures less than that of the wood or wood composite panel, but affords a range which is entirely sufficient fortemperaturescommonlyencounteredinroofingapplications. Funher,theopen-cell foam provides much better insulation per unit thickness than the wood or wood composite panel The open-cell foam has a heat distonion temperature of from 175F to 210F (79Cto99C)andmorepreferablyfrom l9ûFto205F(88Cto96DC)accordingtoASTMD-2126-87 The high heat distonion temperature of the foam enables it to be employed in high service temperatureenvironments~l75Fto210F)(79Cto99C)suchasunderneathdarkroofing membranes in direct sun~ight. The present foam has an excellent heat distonion temperature due to its open-cell structure.
The open-cell foam has an open cell content of 30 percent or more, preferably of30to80percent,andmostpreferabiy40to60percentaccordingtoASTMD2856-87.
The open-celi foam has a density of l .S pcf to 6.0 pcf (24 kg/m3 to 96 kg/m3) and preferably a density of 2.0 pcf to 3.5 p~f (32 kg/m3 to 48 kg/m3) according to ASTM D- 1622-88.
The open-cell foam has an average cell size of from 0.08 millimeters (mm) to 1.2mm and preferably from 0.10 mm to 0.9 mm according to ASTM D3576-77.
The open-cell foam is panicularly suited to be formed into a plank, desirably one having a minor dimension in cross-section (thickness) of greater than 0.25 inches (6.4 millimeters) or more and preferably 0.375 inches (9.S millimeters) or more. Funher, pre1erably, the foam has a cross-sectional area of 30 square centimeters (cm) or more.
The open-cell foam is substantially non-crosslinked. Substantially non-crosslinked means the foam is substantially free of crosslinking, but is inclusive of the slight degree of crosslinking which may occur naturally without the use of crosslinking agents or radiation. A
substantially non-crosslinked foam has less than S percent gel per ASTM D-2765-84, method A.
The open-cell foam comprlses an alkenyl aromatic polymer material . Suitable alkenylaromaticpolymermaterialsincludealkenylaromaticho,,.o,uoly,,._~,andcopolymersof alkenyl aromatic compounds and .opol). ~ ethylenically unsaturated ~u..~ . The alkenyl aromatic polymer material may further include minor proponions of non-alkenyl aromatic polymers. The alkenyl aromatic polymer material may be comprised solely of one or _5_ SUc~STlTUTE SHEET (RULE 26) .. . . . _ ..

w096~0033~ 218,9,6~,3 ~ 26l ~
more alkenyl aromatic homopolymers, one or more alkenyl aromatic copolymers, a blend o~
one or more of each of alkenyl aromatlc l~vl~c"~ul yl "~, s and copolymers, or b~ends of any o i the foregoing with a non-alkenyl aromatic polymer. Regardless of composition, the alkenyl aromatic polymer material comprises greater than S0 and preferably greater than 70 weigh~
percent alkenyl aromatic monomeric units Most preferably, the alkenyl aromatic polymer material is comprised entirely of alkenyl aromatic monomeric units.
Suitable alkenyl aromatic polymers include those derived from alkenyl aromatic compounds such as styrene, alphamethylstyrene, ethylstyrene, vinyl benzene, vinyl toluene, chlorostyrene, and bromostyrene A preferred alkenyl aromatic polymer is polystyrene. Minor amounts of monoethylenically unsaturated compounds such as C2-6 alkyl acids and esters, ionomeric derlvatives, and C4 6 dienes may be .opol~ .l with alkenyl aromatic compounds, Examples of copolymerizable compounds include acrylic acid, methacryllc acid, ethacrylic acid, maleic acid, itaconic acid, acrylonitrile, maleic anhydride, methyl acrylate, ethyl acrylate, isobutyl acrylate, n-butyl acrylate, methyl methacrylate, and vinyl acetate The foams are preferably substantially free of rubbery or rubber-like substances such as those with C4 diene monomeric content. Preferred foams comprise substantially (that is, greater than 9S
percent) and most preferably entirely of polystyrene The open-cell foam is generally prepared by heating an alkenyl aromatic polymer material to form a plasticized or melt polymer material, il~.o",c" a~il)y therein a blowlng agent to 'orm a foamable gel, and extruding the gel through a die to form the foam product. Prior to mixing with the blowing agent, the polymer material is heated to a temperature at or above its glass transition temperature or melting point The blowing agent may be incorporated or mixed into the melt polymer material by any means known in the art such as with an extruder, mixer, or blender. The blowing agent is mixed with the melt polymer material at an elevated pressure sufficient to prevent substantial expansion of the melt polymer material and to generally disperse the blowing agent l)o~)~,y~"eously therein. A nucleating is blended in the polymer melt or dry blended with the polymer material prior to plasticizing or melti ng. The foamable gel is typically cooled to a lower temperature to optimize or attain desired physical characteristicsofthefoam. Thegelmaybecooledintheextruderorothermixingdeviceorin separate coolers. The gel is then extruded or conveyed through a die of desired shape to a zone of reduced or lower pressure to form the foam The zone of lower pressure is at a pressure lower than that in which the foamable gel is maintained prior to extrusion through thedie. Thelowerpressuremaybesup-:-dll,.v>~,l-el-icorsubatmospheric(evaCuatedor ,.
vacuum), but is preferably at an atmospheric level.
More specifically, the foam may be prepared by: a) heating an alkenyl aromatic polymer material comprising more than S0 percent by weight alkenyl aromatic monomeric units to form a melt polymer material; b) incorporating into the melt polymer material an smount of a nucleating agent sufficient to result in a foam having from 30 percent to 80 SU8~vTlTLlTE SHEET (RULE 261 Wo 9610033~ 2 1 8 9 G 6 3 PCT/US9',/0.1261 percent open cell content; c~ Incorporating into the melt polymcrmaterial a~ an elevated pressure a blowing agent to form a foamable gel; d) cooling the foamable gel tO a suitable foaming temperature; and e) extruding the foamable gel through a die into a region of lower pressuretoformthefoam Thefoamingtemperaturerangesfroml18Cto145Cwhereinthe foaming temee~fature Is from 3C to l 5C higher than the highest foaming temperatu~e for a ~,"~,~,ol..l."c~closed-cellfoam Thefoamingtemperaturemustbe133Cormore. The foaming temperature further must be 33~C or more higher than the glass transitlon temperature (according to ASTM D-3418) of the alkenyl aromatic polymer material.Any blowing agent useful in making extruded alkenyl aromatic polymer foams maybeemployed. Useful blowingagentsinclude 1~chloro-1,1-difluoroethane(HCFC-142b), chlorodifluoromethdne(HCFC-22), l,l-difluoroethane~HFC-152a), l,1,1-trifluoroethane(llFC-143a), 1,1,1,2-tetrafluoroethane(HFC-134a),waterethanol,carbondioxide,ethylchloride,and mixtures of the foregoing A preferred blowing agent comprises a mixture of ~arbon dioxide and ethyl chloride.
The amount of nucleating agent employed will vary accofding to desired cell size, foaming temperature, and composition of the nucleating agent. .Open-cell content increases with increasing nucleating agent content. Useful nucleating agents include calcium carbonate, calcium stearate, talc, clay, titanium dioxide, silica, barium stearate, diatomaceous earth, and mixtures of citric acid and sodium bicarbonate. Preferred nucleating agents are talc and calcium stearate. The amount of nucleating agent employed may range from 0.01 to S parts by weight per hundred parts by weight of a polymer resin. The preferred range is from 0 4 to 3.0 parts by weight.
Extensive teachings to the preparation of the open-cell foam are seen in co-pending application U.S. Serial No. 08/264,669, filed June i3, 1994.
The open~cell foam optionally further comprises carbon black. Carbon black enhances the thermal resistance or insulation of the foam. The carbon black may comprise between1.0and25weightpercentandpreferablybetween40and10.0weightpercentbased upon the weight of the alkenyl aromatic polymer material in the foam . The carbon black may be of any type known in the aft such as furnace black, thermal black, acetylene black, and channel black. A preferred cafbon black is thermal black A preferred thermal black has an average particle size of 150 nanometers or more.
Small amounts of an ethylene polymer such as linear low density polyethylene or high density polyethylene may be ;".~ ",u,a~d into the foamable gel to enhance open-cell content upon extrusion and foaming.
Various additives may be in~c."...-dL~-I in the foam such as inorganic fillers, pigments, al ILI~/A;Jal ,~,, acid scavengers, ultraviolet absorbers, flame retardants, processing aids, and extrusion aids.

SUBSTITUTE SHEET (RULE 26) W0 96/00335 ~!18 9 6 6 3 r ~ .0 ~6l ~
The follow~ng are examples of the present invention, and are not to be construedas limiting. Unless otherwise indicated, all percentages, parts, or proportions are by weight.
Open-cell alkenyl aromatic polymer foam structures of the present invention are made according to the process of the present invention.
ExamPie 1 An open-cell extruded polystyrene foam was tested for dimensional stability al 2û5F for 3 hours according to test method ASTM D2126-87. The heat distortion characteristics of the foam were excellent. The length difference was û.2 percent of initial, the width difference was -0.1 percent of initial, and the thickness difference was û.2 percent of initial.
The foam had Sû to 70 percent open cell content, 2.19 pcf (35 kg/m3), and a û.3ûmillimeter cell size ExamPle 2 _ . _ .. . -- -- - - -An open-cell extruded polystyrene foam was tested tor bowing when one side was exposed A Thermotron FM-46 oven with minimum inner dimensions of 42 inches ~ iû7 cm) by 38 inches (97 cm) and a capability of maintaining a const3nt temperatu~e 2û5F ~ 5F was used. The foam was attached to a wooden platform with four metal corner fasteners in the oven. The platform was left in place for the desired period of time The foam was exposed to a temperature of 200F for 30 minutes while the other side supported by a wooden platform 2 remained at ambient conditions, The bowing characteristics of the foam were excellent considering the extreme temperature tonditions to which the foam was exposed. The maximum bow was an average of 17millimeters. Bowingwasdeterminedbymeasuringthedistancefromthebottomofthe foamtotheplatform. If thefoamswereplacedonaroofunderamembrane,bowingwould be less because of the restraining influence of the membrane. Under normal hot-roof conditionsunoeramembrane,suchasexposuretemperaturesof 190Forless,preferredfoamswould have a maximum bow of not more than 6 millimeters.
The sample had 50 to 70 percent open cell content, 2.19 pcf ~35 kglm3), and a 0.3û
millimeter cell si2e.
Whilee,l.L-.,d."l.,l~ofthefoamandtheprocessofthepresentinventionhave been shown with regard to specific details, it will be appreciated that depending upon the manufacturing process and the manufacturer's desires, the present invention may be modified byvariouschangeswhilestillbelngfairlywithinthescopeofthenovelteachingsandprincipies herein set forth SUBSTITUTE SHEET ~RULE 26)

Claims (8)

1. A process for constructing a roofing system for a structure, comprising:
a) providing a roof deck;
b) applying above and adjacent the roof deck a protective layer of a plurality of panels of a foam; and c) applying a substantially waterproof membrane above and adjacent to the foam panels, the process being characterized in that the foam is an extruded alkenyl aromatic polymer foam containing greater than 50 percent by weight alkenyl aromatic monomeric units and having 30 percent or more open cell content.
2. The process of Claim 1, wherein the membrane is applied contiguously to the protective layer.
3. The process of Claims 1 and 2, wherein the system further comprises applying a paving layer above and adjacent the membrane.
4. A process for constructing a replacement roofing system for a structure, comprising:
a) providing a pre-existing roofing system, comprising:
i) a roof deck; and ii) a first membrane situated above and adjacent the roof deck;
b) applying above and adjacent the pre-existing roofing system a protective layer of a plurality of panels of a foam; and c) applying above and adjacent to the foam panels a second membrane which is substantially waterproof, the process being characterized in that the foam is an alkenyl aromatic polymer foam containing greater than 50 percent by weight alkenyl aromatic monomeric units and having 30 percent or more open cell content.
5. The process of Claim 4, wherein the second membrane is applied contiguously to the protective layer
6. The process of any of Claims 1-5, wherein the process is further characterized in that the foam has a minor dimension in cross-section of greater than 6.4 millimeters, the foam having an open cell content of 30 to 80 percent, the foam having a density of 24 to 96 kilograms per cubic meter, the foam having an average cell size of 0.08 millimeters to 1.2 millimeters, the foam having a heat distortion temperature of 79°C to 99°C, the foam being of polystyrene, the foam containing a nucleating agent.
7. The process of any of Claims 1-5, wherein the process is further characterized in that the foam has a minor dimension in cross-section of 9.5 millimeters or more, the foam having an open cell content of 40 to 60 percent, the foam having a density of 32 to 48 kilograms per cubic meter, the foam having an average cell size of 0.1 millimeters to 0.9 millimeters, the foam having a heat distortion temperature of 88°C to 96°C, the foam being of polystyrene, the foam containing a nucleating agent.
8. The process of any of the above claims, the process being further characterized in that the panels do not bow more than 6 millimeters upon exposure to elevated temperatures for an extended period of time.
CA002189663A 1994-06-23 1995-04-06 Open-cell foams in roofing systems Abandoned CA2189663A1 (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US26467794A 1994-06-23 1994-06-23
US08/297,356 US5557896A (en) 1994-06-23 1994-08-29 Method of employing an extruded open-cell alkenyl aromatic foam in roofing systems
US08/264,677 1994-08-29
US08/297,356 1994-08-29

Publications (1)

Publication Number Publication Date
CA2189663A1 true CA2189663A1 (en) 1996-01-04

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CA002189663A Abandoned CA2189663A1 (en) 1994-06-23 1995-04-06 Open-cell foams in roofing systems

Country Status (5)

Country Link
US (1) US5557896A (en)
EP (1) EP0766768A1 (en)
JP (1) JPH10502144A (en)
CA (1) CA2189663A1 (en)
WO (1) WO1996000335A1 (en)

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EP0766768A1 (en) 1997-04-09
US5557896A (en) 1996-09-24
WO1996000335A1 (en) 1996-01-04
JPH10502144A (en) 1998-02-24

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